This invention relates generally to the art of optical holography, and more particularly to composite holography, sometimes referred to as lenticular or multiplex holography.
Techniques for making and using drum shaped composite holograms were developed many years ago. A brief description of such holograms is given on page 95 of the October 1976 issue of Scientific American as part of an article by Emmett N. Leith entitled "White-Light Holograms" beginning at page 80. Briefly, a three-dimensional object is first photographed in an ordinary manner from all sides. Individual narrow lenticular holograms are then formed on a continuous holographic detector material that is subsequently formed into a drum. Each lenticular hologram is constructed from a single ordinary photograph transparency of the three-dimensional object that was earlier taken. Upon white light illumination of the hologram a three-dimensional image of the originally photographed object appears to the observer to exist in the middle of the hologram drum. The observer may walk around the drum and thus around the image of the object. If the object is moved during the photography of it, the resulting holographically reconstructed image will also shown that motion as the observer walks around the drum.
One system is presently being marketed and used by several businesses to make composite holograms. This system is referred to as the "Cross" system, named after its developer Lloyd Cross. This system for constructing the lenticular hologram first magnifies the transparency equally in all directions and forms an image a distance from the hologram detector equal to the radius of the resulting hologram drum. A very large cylindrical lens is placed in this image plane and focuses the light in the horizontal direction so that it fits into the small lenticular hologram aperture. The hologram is made with coherent visible light.
It is a principle object of the present invention to provide a technique and system for making a lenticular hologram capable of reconstructing a sharper and brighter image that fills more of the space within the center of the drum than do lenticular holograms made with existing techniques, and to eliminate vertical lines from the reconstructed image.
It is another object of this invention to provide a technique which allows for an undistorted visible image to be reconstructed from the drum hologram, even though the hologram is constructed with non-visible radiation.
It is a further object of the present invention to provide a technique for making a master lenticular hologram that is suitable for economical mass replication thereof.